Method of and apparatus for grinding and polishing



June 13, 1939. H. R. HERCHENRIDER 2,162;279

METHOD OF AND APPARATUS FOR GRINDING AND POLISHING Filed July 30, 1938ATTORNEY.

Patented June 1939 PATENT OFFICE METHOD OF AND APPARATUS FOR GRIND- INGAND POLISHING Henry R. Herchenrider, Pittsburgh, Pa., assignor toMinnesota Mining & Manufacturing Company, St. Paul, Minn, a corporationof Delaware Application July so, 1938, Serial No. 222,266

4 Claims. (01. 51-139) My invention relates to grinding and polishingapparatus, and more particularly to an improved form of roll, wheel ordrum, employed for bringing the abrasive into-contact with the metalsheets or other material being ground or polished.

The roll is particularly designed for use as a presser roll in that itis employed for holding or backing up an abrasive belt or strip in orderto provide for pressure thereon during a grinding or polishingoperation. In structures of this character, it is desirable that thesurface of the presser roll be hard enough to permit of sufiiclentpressure against the abrasive-carrying belt to maintain grindingpressure that will permit continued use of the belt after the sharpeststructure of the abrasive has been worn down somewhat, until a point atwhich substantially all of the abrasive has been consumed or used up.

If a roll is employed that is rigid across its entire diameter, itcannot yield at various surface areas thereof in such manner as topermit it to follow the contour of an uneven or non-plannlar surfacebeing ground. Also,'there is tendency toward chattering of suchhard-bodied rolls. On the other hand, if a soft-surfaced presser roll isemployed, there would be a tendency for the abrasive grains to be pushedbackwardly into or toward the roll, with the result that such grains arenot pressed against the work with sufficient firmness.

One object of my invention is to provide a roll of such constructionthat the surface thereof will be of sufficient hardness to provide forsuch rigid pressure against the belt as to firmly maintain the abrasivegrains in contact with the work, and to resist the receding ordeflection of the grains under grinding pressure in a direction towardthe center of the roll, and at the same time to provide a roll body ofsuflicient yieldability to permit localized areas of the hardenedperipheral surface to recede somewhat toward the axis of the roll, undergrinding pressure, so that the roll can conform to uneven or irregularareas on the surface beingground.

The invention is particularly useful in connection with the grinding andpolishing of miscellaneous articles and also steel strips and sheets.

Broadly stated, the invention embodies a presser roll mounted on a shaftand having a core of soft material such as soft rubber, upon theperipheral surface of which core is mounted blocks or strips of hardmaterial that bear against an abrasive-carrying belt. By using arollwhose body is yieldable but whose peripheral surface is composed of hardblocks, each of which may yield radially independently of the other,against the soft body or core, I avoid the objections to the use ofeither all-hard or all-soft rolls when employed to back up a sandingbelt.

Some of the forms which my invention may take are shown in theaccompanying drawing wherein Figure 1 is a longitudinal sectional Viewthrough a grinding or polishing machine; Fig. 2

is a sectional view on an enlarged scale of a portion of the structureof Fig. 1; Fig. 3 is a side view of the presser roll, partly in section;Fig. 4 is a view showing hard presser blocks of different form thanthose shown in Fig. 3; Fig. 5 is a view taken on the line V-V of Fig. 4;Fig. 6 shows another form of presser roll mounted in a grinding machineof a different type than that shown in Fig. 1, and Fig. 7 is an end viewof the structure of Fig. 6.

Referring first to Figs. 1 to 3, the numeral I0 represents one of theside frames of a grinding or polishing machine. A series of guide andsupporting rollers II and I2 are journalled in the pair of side framesII], as are also pairs of guiding or feed rolls I3 and I4, either orboth of which may be driven from a suitable source of power to advance ametal sheet or strip I5 through the machine. A billy roll I6 isjournalled at each end in bearing blocks H, the bearing blocks beingvertically adjustable in the side frames III by means of adjustingscrews I8 that have screw threaded engagement with brackets I9. Eachscrew I8 operates against a block 20 which serves as a seat for a spring2| that is interposed between the spring seat and the bearing block I7,so that the pressure of the roll I6 and the resistance thereof todownward thrusts can be adjusted.

In the upper part of the framework Ill, pulleys 22 and 23 arejournalled, and a sanding belt 24 passes around the pulleys. A motor 25is provided to drive the pulley to effect movement of the abrasive belt.A presser roll 26 isjournalled in the machine and serves to hold thebelt 24 in grinding engagement with the work I5.

The roll 26 comprises a shaft 21, a soft core or body portion 28' ofrubber or other suitable material, and a facing of hard blocks or shoes29 which maybe of hard rubber, cork or steel, vulcanized or cemented tothe soft core 28. As shown more clearly in Fig. 3, the blocks 29 are ofsquare or rectangular form, sufficient clearance being providedbetweenthe blocks to permit individual blocks to be deflected relative to theother blocks when encountering uneven areas on the work being ground. Byreason of the pressure upon the abrasive'belt and to offer sumcientresistance to any tendency for the abrasive grains to recede from thework under grinding pressure. when the presser roll 23 is 'iournalled ona ilxed axis, the grinding pressure can be varied by adjusting thescrews I3.

The outermost corners of the blocks 23 are slightly rounded so that thepresser wheel will engage the belt 24 more smoothly and thus avoid sharpdeflections of the belt along the lines where it is engaged by theblocks, and also reduce danger of cutting or tearing the belt.

Instead of forming the ,blocks 23 of a very hard material, they may beof less rigid material such as of hard rubber which is not bonehard, orhard cork which is of greater rigidity I than the rubber core. Thesewould be useful in connection with the grinding and polishing ofmaterials such as the softer metals wherein the harder blocks are notdesired to effect proper abrading action or pressure, because the harderblocks would tend to push the abrasive too deeply into the softer metalsand cause the abrasive.

grains to be torn loose, causing rapid grain loss from the abrasivebelt. 7

Referring now to Figs, 4 and 5, I show a modification of the form ofpresser roll shown in Figs. 1 to 3, in that instead of the rectangularshaped hard blocks 23, I employ blocks 3! of diamond shape, mounted on asoft core or backing 32, wherein the leading edges of the blocksgradually enter into engagement with the belt, because of the angularlines of such edges, it being seen that the blocks will in efl'ect bebrought into point contact with the belt and then be moved progressivelyinto full-faced contact therewith. The blocks 3i also have their comersrounded as shown more clearly in Fig. 5.

In Figs. 6 and 'l I show another manner in which hard-surfaced andsoft-cored rolls may be employed. In this instance a motor 33 drives awheel 34 around which an abrasive belt 35 passes, the belt also passingaround a pulley 36. The wheel 34 is provided with'a soft rubber corefaced by hard'blocks 31 which correspond to the blocks 29 and 3|, butare in the form of strips which extend axially across the wheel.

fact that the blocks are of hard material, they provide sufilcientrigidity to permit of adequate This arrangement is employed forpolishing small articles or narrow strips which are manually orotherwise brought into engagement with the belt :2 some point along theperiphery of the wheel It will be understood that the cores of thepresser rolls may be of desired degrees of softness as, for example, 20to standard rubber hardness durometer gauge.

I claim as my invention:

1. A grinding and polishing machine comprising an abrasive belt or thelike, means for moving said belt, and a presser roll for holding saidbelt against materials being ground or polished, during movement of thebelt, the said roll having a soft core which-supports blocks of hardermaterial disposed peripherally thereof for engagement with said belt.

2. A grinding and polishing machine comprising an abrasive belt or thelike, means for moving said belt, and a presser roll for holding saidbelt against materials being ground or polished, during movement of thebelt, the said roll having a soft core which supports blocks of hardermaterial, each of which extends from end-toend of the roll and which aredisposed peripherally thereof for engagement with the said belt.

3. A grinding and polishing machine comprising a flexibleabrasive-carrying element, means for moving said element. and a presserroll for holding said element against materials being surfaced, duringmovement of the element, the said roll having a soft core that supportsdiamondshaped blocks of harder material which are arranged in rowsextending axially and peripherally of the roll, the blocks of each rowbeing in partially interspersed relation with the blocks of adjacentrows.

4. A grinding and polishing machine comprising an abrasive belt or thelike, means for moving said belt, and a presser roll for holding saidbelt against materials being ground or polished, during movement of thebelt, the said roll having a soft core which supports blocks of hardermaterial disposed peripherally thereof for engagement with said belt,the said core being of materially greater thickness than the saidblocks.

HENRY R. HERCHENRIDER.

